Ubuntu 13.10 32-bit vs. 64-bit Performance
While there wasn't much change in the Linux gaming performance, as soon as moving to the computational workloads, 64-bit Ubuntu 13.10 was jumping ahead. There are very clear performance advantages to 64-bit Linux on this Lenovo ThinkPad laptop with Intel Core i7 processor.
FFTE and x264 also performed faster "out of the box" on 64-bit Ubuntu over the 32-bit build.
The Linux kernel compilation time really doesn't change much.